Ika Musume

Ika Musume (イカ娘, lit. Squid Girl) is a girl who comes from the sea with plans to invade humanity as punishment for the pollution done to the sea. However, after causing damage to a beach house, she is forced to work as a waitress to pay for the damages and also sleeps at the Aizawa residence. Like a squid, she has ten fully controllable arms that protrude from the top of her head like hair, and can spew squid ink from her mouth, and can glow like a Firefly Squid. She enjoys shrimp and greatly fears natural predators like killer whales, to the point that even swimming floats shaped like killer whales terrify her. According to her, she will die if she takes her hat off. She almost always ends her sentences with "geso" (ゲソ, lit. "arms of squid as food") as a final particle and emphasizes "ika" in sentences, which is reflected by how it's written (e.g.: ja na ika (～じゃなイカ, lit. isn't it?)).

Although she regularly fails to accomplish her goal to invade humanity, Ika Musume proves to be a master at just about everything else, something she herself eventually ends up admitting. Her tentacles are very strong, incredibly dexterous and she can control them effortlessly; they also can stretch to a huge range, and they have a variety of offensive capabilities; she can deliver a powerful smack, wrap them around a foe and hoist them into the air, or coerce them through tickling. They also have more practical uses- she is an asset to the beach house as she can carry many plates at once, drawing with her tentacles results in hyper-detailed masterpieces, and she excels at other physical activities such as volleyball and drumming. Despite her usual naivety, she also displays a high level of intelligence occasionally- it is revealed she is a mathematical genius, capable of working with such functions as the Fourier analysis and the Poisson summation formula, and Chizuru notes how quickly she learned how to speak Japanese and interact with humans. Ika Musume always considers twisting her talents to use as an advantage in dominating humans, but her childlike ways make it difficult for her to be taken seriously, and she is easily distracted, bribed and fooled by the others.

Trivia

• Excluding the cosplay she is forced to go through by Sanae, Ika Musume is only ever seen through the series in one of two outfits, her white and blue dress, or a white one piece swimsuit.
• Unlike normal cephalopods which typically propel themselves through jet propulsion, Ika Musume swims by using her tentacles to propel her forwards in the water with successive thrusts in the water. While she is naturally able in the water, Ika Musume is utterly incapable of swimming in the water using her arms and feet the way humans do. Additionally her tentacles can be extended so long she can float stationarity at the surface of deep water by supporting herself with her tentacles.